U.S. patent application number 14/024157 was filed with the patent office on 2014-10-16 for planar rf crossover structure with broadband characteristic.
This patent application is currently assigned to Electronics and Telecommunications Research Institute. The applicant listed for this patent is Electronics and Telecommunications Research Institute. Invention is credited to Jae Ick CHOI, Soon Young EOM, JeongHo JU, Joung Myoun KIM, Myung Sun SONG.
Application Number | 20140306776 14/024157 |
Document ID | / |
Family ID | 51686395 |
Filed Date | 2014-10-16 |
United States Patent
Application |
20140306776 |
Kind Code |
A1 |
EOM; Soon Young ; et
al. |
October 16, 2014 |
PLANAR RF CROSSOVER STRUCTURE WITH BROADBAND CHARACTERISTIC
Abstract
An RF crossover structure includes a first and second
independent transmission lines formed to cross with each other on a
same surface of a dielectric substrate; first via-holes connected
to the second transmission line so that the second transmission
line is connected to a back surface from a front surface of the
dielectric substrate and is connected again to the front surface of
the dielectric substrate out of a crossing region at which the
first and the second transmission lines are crossed. Further, the
RF crossover structure includes CPW (Coplanar Waveguide)
transmission lines used for a ground plane to improve a signal
transmission property at the crossing region.
Inventors: |
EOM; Soon Young; (Daejeon,
KR) ; KIM; Joung Myoun; (Daejeon, KR) ; JU;
JeongHo; (Daejeon, KR) ; SONG; Myung Sun;
(Daejeon, KR) ; CHOI; Jae Ick; (Daejeon,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Electronics and Telecommunications Research Institute |
Daejeon |
|
KR |
|
|
Assignee: |
Electronics and Telecommunications
Research Institute
Daejeon
KR
|
Family ID: |
51686395 |
Appl. No.: |
14/024157 |
Filed: |
September 11, 2013 |
Current U.S.
Class: |
333/1 ;
333/246 |
Current CPC
Class: |
H01P 5/028 20130101;
H01P 3/003 20130101 |
Class at
Publication: |
333/1 ;
333/246 |
International
Class: |
H01P 5/00 20060101
H01P005/00; H01P 3/08 20060101 H01P003/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 16, 2013 |
KR |
10-2013-0041519 |
Claims
1. An RF crossover structure comprising: a first and second
independent transmission lines formed to cross with each other on a
same surface of a dielectric substrate; first via-holes connected
to the second transmission line so that the second transmission
line is connected to a back surface from a front surface of the
dielectric substrate and is connected again to the front surface of
the dielectric substrate out of a crossing region at which the
first and the second transmission lines are crossed; and CPW
(Coplanar Waveguide) transmission lines used for a ground plane to
improve a signal transmission property at the crossing region.
2. The RF crossover structure of claim 1, further comprising second
via-holes that connect the CPW transmission line to a ground plane
on the back surface of the dielectric substrate.
3. The RF crossover structure of claim 2, wherein the CPW
transmission lines are configured to compensate the signal
transmission property due to a mutual coupling at the crossing
region between the first and second transmission lines.
4. The RF crossover structure of claim 3, wherein the signal
transmission property comprises an input/out matching
characteristic or change in impedance.
5. The RF crossover structure of claim 1, wherein the CPW
transmission lines are configured to have the same impedance
characteristic as the input/output characteristic impedances in
order to isolate the second transmission line that is connected to
the back surface of the dielectric substrate through the structure
of the via-holes from the ground plane.
6. The RF crossover structure of claim 1, further comprising: a
slot-loop formed in the form of a rectangle in the vicinity of the
second transmission line on the back surface of the dielectric
substrate in order to improve a signal transmission property.
7. The RF crossover structure of claim 1, wherein the first and
second transmission lines have a conductive area of which a portion
is eliminated in a certain form so that a signal coupling region is
set to be a predetermined area and the signal coupling region of
the first and second transmission lines that are perpendicular to
each other on different surfaces of the dielectric substrate is
reduced to a predetermined range.
8. The RF crossover structure of claim 7, wherein the conductive
area that is eliminated is formed in a diamond shape or a
rectangular shape.
9. The RF crossover structure of claim 1, wherein the first and
second transmission lines are formed at a center cross section on
the dielectric substrate, and wherein the first and second
transmission lines have a structure of a strip line with two ground
planes.
10. The RF crossover structure of claim 9, wherein the center cross
section has one CPW crossing transmission line, and another CPW
crossing transmission line implemented thereon, wherein the another
CPW crossing line is formed on one of the two ground planes.
11. An RF crossover structure comprising: an RF transmission line
formed on a first surface of a dielectric substrate; and DC
power/control lines formed on a second surface of the dielectric
substrate to cross with the RF transmission line at a crossing
region, wherein the RF transmission line is formed to have a
structure of a CPW (Coplanar Waveguide) transmission line at the
crossing region.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] The present invention claims priority of Korean Patent
Application No. 10-2013-0041519, filed on Apr. 16, 2013, which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a compact RF crossover
structure with broadband characteristic and high isolation, and
more particularly, to a planar RF crossover structure in which two
orthogonal independent first and second microstrip transmission
lines are formed on the same surface to cross over each other, and
the crossing region of the first and the second microstrip
transmission lines are formed on different surfaces, wherein a
first microstrip transmission line extends from a first (top)
surface, and a second microstrip transmission line runs to a second
(bottom) surface from the first surface through a via-hole
connection structure and is out of the crossing region to extend to
the first surface again through a via-hole connection structure,
and a structure of CPW (Coplanar Waveguide) transmission line is
formed on the crossing region to keep the same characteristic
impedance.
BACKGROUND OF THE INVENTION
[0003] Typically, an important feature of the microstrip structure
is that it is able to integrate complex circuits within a planar
structure. However, as the complexity of a microwave circuit is
increased, there may occur a problem that independent transmission
lines are crossed, which leads to degradation of circuit
performance and will disturb the optimization of circuit size.
[0004] RF crossover components provide the ability to allow two
independent transmission lines to cross within permissible
isolation performance and thus make it possible to simply implement
complex microstrip circuits. In particular, the RF crossover is
often used in a multi-beam forming circuitry (used in the Butler
matrix structure) and a microwave system that requires complex
connections or wirings such as microwave switch matrixes.
[0005] As shown in FIGS. 1A, 1B and 1C, conventional RF crossover
structures include wire bonding or air bridge structure, a
structure with an impedance compensation circuit around crossed
transmission lines, a cascaded 90.degree. hybrid coupler structure
and the like.
[0006] The wire bonding structure as shown in FIG. 1A is the
simplest RF crossover structure. This wire bonding structure
suffers from a process in which a wire is connected in the air
while maintaining a certain height, which affects input/output
impedance matching and an isolation characteristic. That is, if a
height from the bottom increases, the isolation performance is
improved, but the impedance matching characteristic becomes
degraded. Accordingly, these above characteristics need to be
considered in a mutual compromise. Such a simple RF crossover
structure has a disadvantage to require an additional processing
such as wire bonding after a PCB fabrication. Therefore, it is
often used in an MMIC process.
[0007] FIG. 1B shows an RF crossover with an impedance compensation
circuit around crossed transmission lines. The width of crossed
transmission lines is reduced in order to improve a mutual
isolation characteristic, and additional circuitries are disposed
around the transmission lines in order to compensate for the
impedance mismatching characteristic due to the reduced width. This
structure has drawbacks such as an increased size owing to the
additional circuitries and a narrow band characteristic.
[0008] Further, as shown in FIG. 1C, a cascaded 90.degree. hybrid
coupler structure has a configuration in which a pair of 90.degree.
hybrid couplers is connected in series to allow crossing
independent two transmission lines with each other. However, this
structure has a disadvantage of an increase in a circuit size, an
increase of an insertion loss due to an increased length of the
transmission lines, and a narrow-band characteristic owing to the
electrical characteristics of the cascaded 90.degree. hybrid
structure.
SUMMARY OF THE INVENTION
[0009] In view of the above, the present invention provides a
planar RF crossover structure in which two independent first and
second microstrip transmission lines are formed on the same surface
to cross with each other, and the crossing region of the first and
the second microstrip transmission lines are formed on different
surfaces, wherein a first microstrip transmission line extends from
a first surface (top), and a second microstrip transmission line
runs to a second surface (bottom) from the first surface through a
via-hole connection structure and is out of the crossing region to
extend to the first surface again through the via-hole connection
structure, and a structure of CPW transmission line is formed on
the crossing region to achieve a signal transfer property.
[0010] In accordance with an embodiment of the present invention,
there is provided an RF crossover structure including: a first and
second independent transmission lines formed to cross with each
other on a same surface of a dielectric substrate; first via-holes
connected to the second transmission line so that the second
transmission line is connected to a back surface from a front
surface of the dielectric substrate and is connected again to the
front surface of the dielectric substrate out of a crossing region
at which the first and the second transmission lines are crossed;
and CPW (Coplanar Waveguide) transmission lines used for a ground
plane to keep the same characteristic impedance at the crossing
region.
[0011] Further, the RF crossover structure may further comprise
second via-holes that connect the CPW transmission line to a ground
plane on the back surface of the dielectric substrate. Further, the
CPW transmission lines may be configured to compensate the signal
transmission property due to a mutual signal coupling at the
crossing region between the first and second transmission
lines.
[0012] Further, the signal transmission property may comprise an
input/out impedance matching characteristic or change in
impedance.
[0013] Further, the CPW transmission lines may be configured to
have the same impedance characteristic as the input/output
characteristic impedances in order to isolate the second
transmission line that is extended to the back surface of the
dielectric substrate through the structure of the via-holes from
the ground plane.
[0014] Further, the RF crossover structure may further comprise a
slot-loop formed in the form of a rectangle in the vicinity of the
second transmission line on the back surface of the dielectric
substrate in order to improve a signal transmission property.
Further, the first and second transmission lines may have a
conductive area of which a portion is eliminated in a certain form
so that a signal coupling region is set to be a predetermined area
and an amount of a mutual signal coupling of the first and second
transmission lines that are perpendicular to each other on
different surfaces of the dielectric substrate is reduced to a
predetermined range.
[0015] Further, the conductive area that is eliminated may be
formed in a diamond shape or a rectangular shape.
[0016] Further, the first and second transmission lines may be
formed at a center cross section on the dielectric substrate and
have a structure of a strip line with two ground planes.
[0017] Further, the center cross section may have one CPW crossing
transmission line and another CPW crossing transmission line
implemented thereon, and the another CPW crossing line is formed on
one of the two ground planes.
[0018] Further, one surface of the dielectric substrate may have an
RF transmission line implemented thereon, another surface has a DC
(Direct Current) power/control line to be crossed at a certain
region, the RF transmission line being formed to have a structure
of a CPW (Coplanar Waveguide) transmission line at the crossing
region.
[0019] In accordance with an embodiment of the present invention,
two independent first and second microstrip transmission lines are
formed on the same surface to cross with each other, and the
crossing region of the first and the second microstrip transmission
lines are formed on different surfaces, wherein a first microstrip
transmission line extends from a first surface, and a second
microstrip transmission line runs to a second surface from the
first surface through a via-hole connection structure and is out of
the crossing region to connect to the first surface again through
the via-hole connection structure, and a structure of CPW
transmission line is formed on the crossing region, thereby
achieving a superior signal transmission property.
[0020] Further, in accordance with the crossover structure of the
embodiment of the present invention, it is possible to reduce the
size of the RF crossover circuit significantly and enhance the
electrical properties such as an excellent input/output matching,
an isolation characteristic between the transmission lines and a
low insertion loss in microwave circuits to need RF crossover
elements such as the Butler matrix for the multi-beam
formation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The above and other objects and features of the present
invention will become apparent from the following description of
the embodiments given in conjunction with the accompanying
drawings, in which:
[0022] FIGS. 1A, 1B and 1C are exemplary diagrams of conventional
RF crossover structures;
[0023] FIGS. 2A to 2D are exemplary diagrams that are implemented
on a double-sided substrate in accordance with a first embodiment
of the present invention;
[0024] FIG. 3 shows a structure of a co-planner waveguide
transmission line in accordance with an embodiment of the present
invention;
[0025] FIGS. 4A to 4D illustrate RF crossover structures with an
improved isolation property in accordance with a second embodiment
of the present invention;
[0026] FIGS. 5A and 5B depict shapes of conductive area that is
eliminated in order to enhance an isolation characteristic in
accordance with an embodiment of the present invention;
[0027] FIGS. 6A to 6D illustrate examples of design parameters and
design values of the RF crossover in accordance with an embodiment
of the present invention;
[0028] FIGS. 7 and 8 depict graphs of the experimental results of
S-parameters of the RF crossover structures in accordance with the
embodiments of the present invention;
[0029] FIG. 9 illustrates a graph comparing the isolation
characteristic of RF crossover structures in accordance with
embodiments of the present invention; and
[0030] FIGS. 10A and 10B illustrate a structure of the RF crossover
between an RF transmission line and DC power/control lines in
accordance with a third embodiment of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0031] In the following description of the present invention, if
the detailed description of the already known structure and
operation may confuse the subject matter of the present invention,
the detailed description thereof will be omitted. The following
terms are terminologies defined by considering functions in the
embodiments of the present invention and may be changed operators
intend for the invention and practice. Hence, the terms need to be
defined throughout the description of the present invention.
[0032] Hereinafter, the embodiments of the present invention will
be described in detail with reference to the accompanying drawings
which form a part hereof.
[0033] FIGS. 2A to 2D illustrate an RF crossover structure that
minimizes the change in input/output characteristic impedances at a
crossing region in accordance with a first embodiment of the
present invention.
[0034] An RF crossover has a structure in which two independent
transmission lines intersect perpendicularly with each other. In
the RF crossover, the change in the input/output characteristic
impedances should be minimized at the crossing region to each
other, and an isolation characteristic should be superior so that
there is no mutual coupling between the transmission lines. If
these two conditions are satisfied, it is possible to design an RF
crossover with a low insertion loss, an input/output matching
characteristic and an excellent isolation property.
[0035] Referring to FIGS. 2A to 2D, both surfaces of a dielectric
substrate are used, one side of the substrate is used as a region
in which two perpendicular transmission lines enter and exit, the
other side is used as a ground plane of the transmission lines and
as a connection region to avoid direct crossing between the
transmission lines.
[0036] The RF crossover structure proposed by the embodiment of the
present invention includes a front surface F1000 that has input and
output terminals P1 and P2, and a transmission line TL1 thereon.
The front surface further includes a region which changes from a
microstrip transmission line to coplanar waveguide line to
compensate the characteristic impedance due to deformation of the
ground plane of the transmission line TL1 by the transmission line
TL22 that occurred in the crossing region. In other words, the
region for compensation is composed of the transmission lines
CPW_FG1 and CPW_FG2 that are used for a signal ground of the
crossing region of the transmission line TL1, and two pairs of
via-holes FGV1, FGV2 that are located at both ends of the
transmission line CPW_FG1, CPW_FG2 in order to make the connection
of the transmission lines CPW_FG1, CPW_FG2 with a lower ground
plane.
[0037] Further, the transmission line TL1 the transmission line
TL22 are formed at a center cross section on the dielectric
substrate, and they have a structure of a strip line with two
ground planes.
[0038] The via-holes FGV1, FGV2 presented on the front surface
F1000 of the RF crossover are respectively connected to via-holes
BGV1, BGV2 presented on the back surface B1000. Therefore, the
signal input to the input terminal P1 is transferred to the output
terminal P2 via the microstrip transmission line region, the
coplanar waveguide line (crossing region) and the microstrip
transmission line region. In this regard, the RF crossover is a
reversible circuit, and thus the input and output terminals P1 and
P2 may be changed in reverse.
[0039] Further, the RF crossover structure includes input and
output terminals P3, P4 and the transmission line TL21 on the front
surface F1000 that are independent and located in a direction
perpendicular to each other to the input and output terminal P1, P2
and the transmission line TL1. In addition, the RF crossover
structure includes the transmission line TL22 and a crossing region
located on the back surface B1000 thereof. Moreover, in order to
compensate the characteristic impedance of the transmission line
TL22 considering the mutual coupling, which is occurred in the
crossing region, due to the transmission lines TL1, CPW_FG1,
CPW_FG2, the RF crossover structure further includes a region to
change from the microstrip transmission lines to the coplanar
waveguide lines, i.e., a ground plane CPW_BG1 on the back surface
B1000 to be used for a signal ground provision of the crossing
region of the transmission line TL22.
[0040] In addition, the RF crossover structure further includes a
via-hole FSV1, which allows connecting the transmission lines TL21
and TL22, and a via-hole FSV2, which allows connecting the
transmission lines TL22 and TL23. The via-holes FSV1, FSV2
presented on the front surface F100 of the RF crossover are
connected to the via-holes BSV1, BSV2 presented on the back surface
B100, respectively. In this regard, in order to isolate the ground
plane from the transmission line TL22 connected to the back surface
through the via-holes FSV1, FSV2, and in order to form a coplanar
waveguide line structure with the same characteristic impedance as
the input and output characteristic impedance, the optimal
rectangular slot-loop is formed around the transmission line
TL22.
[0041] Accordingly, the signal input to the input terminal P3 is
transferred to the output terminal P4 through the microstrip
transmission line region, the coplanar waveguide line (crossing
region), and the microstrip transmission line region again. In
relation to this, the RF crossover is a reversible circuit, and
thus the input and output terminals P3 and P4 may be changed in
reverse.
[0042] Meanwhile, a basic coplanar waveguide line as shown in FIG.
3 may be used so that the characteristic impedance of the coplanar
waveguide transmission lines (i.e., TL1 and CPW_FG1, CPW-FG2
regions, and TL22 and CPW_BG regions) that are used in the crossing
region maintains the same as the input/output characteristic
impedances.
[0043] Further, the structure of the basic coplanar waveguide line
as shown in FIG. 3 may be optimally designed using following
Equations 1 to 4. The line width and the gap between the line width
and the ground plane should be adjusted to maintain the
characteristic impedance of the coplanar waveguide line as a
specific value (in this example, 50 W). Among them, the gap greatly
influences on the characteristic impedance. At this time, the
design of the coplanar waveguide line needs also to take into
account the layout pattern shape that is placed on the opposite
side.
Z o = 30 .pi. e .pi. ( k ' ) K ( k ) [ Equation 1 ] e = 1 + r - 1 2
K ( k ' ) K ( k 1 ) K ( k ) K ( k 1 ' ) [ Equation 2 ] K ( k ) K '
( k ) = { [ 1 .pi. ln ( 2 1 + k ' 1 - k ' ) ] - 1 for 0 .ltoreq. k
.ltoreq. 0.7 1 .pi. ln ( 2 1 + k 1 - k ) for 0.7 .ltoreq. k
.ltoreq. 1 [ Equation 3 ] k = A B , A = W 2 , B = W 2 + G , k 1 =
sinh ( 0.5 .pi. AH ) sinh ( 0.5 .pi. BH ) [ Equation 4 ]
##EQU00001##
where K'(k)=K(k'), k'= {square root over (1-k.sup.2)},
.epsilon..sub.e denotes an effective dielectric constant, a
function K represents a perfect primary elliptical function, K'
represents a complementary function of the function K.
[0044] As shown in FIGS. 4A to 4D, a second embodiment of the
present invention proposes an RF crossover structure with both
surfaces F2000/B2000 in order to improve the isolation
characteristic of the RF crossover structure with the both surfaces
F1000/B1000. This RF crossover structure minimizes a signal
coupling region (i.e., a signal coupling capacitance) of
transmission lines TL1 and TL22 perpendicular each other in
different surfaces and increases the thickness of the dielectric,
thereby enhancing the isolation characteristic between the crossing
two transmission lines.
[0045] Further, when a conductive area in the crossing region is
eliminated in order to minimize the signal coupling region, a
non-metalized area at the center of the transmission lines TL1,
TL22 may be formed in any shape such as a diamond shape and a
rectangular shape as shown in FIGS. 5A and 5B, respectively.
[0046] As an example, the planar RF crossover structure proposed by
the embodiment of the present invention was designed using the
design simulator (CST Microwave Studio commercially available) in
order to check the electrical characteristics thereof. A dielectric
substrate used in this design was a TLY-5A substrate commercially
available from Taconic Inc., with a dielectric constant
.epsilon..sub.r=2.17, a thickness of the dielectric H=0.508 mm (20
mils). A thickness of the copper foil T=0.035 mm (1 oz.), and
design parameters and design values for the RF crossover designed
by an example are represented in FIGS. 6A to 6D.
[0047] Referring to FIGS. 6A to 6D, the design parameters and the
design values for the RF crossover structure presented in
accordance with an embodiment are as follows.
[0048] On the front surface F2000 shown in FIG. 6A, W.sub.1=1.56
mm, S.sub.1=0.15 mm, S.sub.2=0.20 mm, D.sub.11=4.00 mm,
D.sub.12=1.00 mm, D.sub.13=2.00 mm, G.sub.1=3.71 mm, G.sub.2=1.00
mm, G.sub.3=2.71 mm, d=0.55 mm.
[0049] On the back surface B2000 shown in FIG. 6B, W.sub.2=1.40 mm,
L.sub.1=6.26 mm, L.sub.2=5.26 mm, G.sub.4=6.66 mm, G.sub.5=1.71 mm,
D.sub.21=3.56 mm, D.sub.22=1.00 mm, and D.sub.23=1.56 mm.
[0050] The RF crossover structure of the first embodiment of the
present invention has the same design parameters and values as
shown in FIGS. 6A to 6D except that it does not have the
non-metalized area with the diamond shape, and its S-parameter
simulation result is shown in FIG. 7.
[0051] That is, FIG. 7 shows the S-parameter simulation result of
the RF crossover structure with the front and back surfaces
F1000/B1000 in accordance with the first embodiment of the present
invention.
[0052] As shown in FIG. 7, the RF crossover structure of the first
embodiment of the present invention exhibits good electrical
characteristics that an insertion loss in the broadband of
0.about.20 GHz is 0.8 dB or less, an input/output matching
characteristic is 19.8 dB or more, and an isolation characteristic
is 17.7 dB or more.
[0053] Further, the design parameters and the design values shown
in FIG. 6 are also entirely kept in the RF crossover structure with
the front and back surfaces F2000/B2000 in accordance with the
second embodiment of the present invention and an S-parameter
simulation result of the RF crossover of the second embodiment is
represented in FIG. 8.
[0054] As shown in FIG. 8, the RF crossover structure of the second
embodiment exhibits the phenomenon that the operating bandwidth is
reduced slightly due to deterioration of the input/output matching
characteristic, but this may be caused by a change in the
characteristic impedance of the transmission lines and may be
improved through optimization of a design process. The RF
crossover, which is designed as one example, has an optimization
frequency band of 0.about.16 GHz and shows excellent electrical
characteristics that an insertion loss in the operating frequency
band is 0.45 dB or less, an input/output matching characteristic is
19.8 dB or more, and an isolation characteristic is 24.8 dB or
more.
[0055] FIG. 9 is a graph comparing the isolation performances of
the RF crossover structures with or without the non-metalized area
at the center portion of the conductive area in the crossing region
of the transmission lines.
[0056] That is, FIG. 9 shows the comparison result of the isolation
characteristic between the RF crossover structures wherein the RF
crossover structure of the first embodiment has not the
non-metalized area within the crossing region of the transmission
lines and the RF crossover configuration of the second embodiment
has the non-metalized area within the crossing region of the
transmission lines. In the RF crossover in which the conductive
area is eliminated in the diamond shape, it is observed that there
is an improvement of about 7 dB in the frequency band of 0.about.20
GHz.
[0057] FIGS. 10A and 10B illustrate a crossover structure formed
between an RF transmission line and DC power/control lines in
accordance with a third embodiment of the present invention.
[0058] Referring to FIGS. 10A and 10B, the RF crossover structure
has a configuration that an RF transmission line F3000 on a front
surface of a dielectric substrate intersects with DC power/control
lines B3000 on a back surface of a dielectric substrate within a
predetermined region.
[0059] In order to compensate an electrical characteristic of the
RF transmission line at a crossing region, i.e., in order to
compensate input/output characteristic impedances, the RF crossover
structure, as the same manner as described in FIGS. 2A to 2D,
includes a region that changes from a microstrip line to a coplanar
waveguide line. In other words, the region is composed of
transmission lines CPW_FG1, CPW_FG2 that are used for a signal
ground of the crossing region on the transmission line TL1 and two
pairs of via-holes FGV1, FGV2 that are located at both ends of the
transmission lines CPW_FG1, CPW_FG2 so that the transmission lines
CPW_FG1, CPW_FG2 can be connected to a ground plane on the back
surface.
[0060] The via-holes FGV1, FGV2 presented on the front surface
F3000 of the RF crossover are respectively connected to the
via-holes BGV1, BGV2 presented on the back surface B3000 of the RF
crossover. Therefore, the signal input to the input terminal P1 is
transferred to the output terminal P2 via the microstrip
transmission line region, the coplanar waveguide line (crossing
region), and the microstrip transmission line region again. In this
regard, the RF crossover is a reversible circuit, and thus the
input/output terminals P1 and P2 may be changed in reverse.
[0061] As described above, in accordance with an embodiment of the
present invention, two independent first and second transmission
lines are crossed each other and the crossing region of the first
and the second transmission lines are formed on different surfaces,
wherein a first transmission line extends from a first surface, and
a second transmission line runs to a second surface from the first
surface through a via-hole connection structure and is out of the
crossing region to connect to the first surface again through the
via-hole connection structure, and a structure of CPW transmission
line is formed on the crossing region to achieve an optimal signal
transmission property.
[0062] While the invention has been shown and described with
respect to the embodiments, the present invention is not limited
thereto. It will be understood by those skilled in the art that
various changes and modifications may be made without departing
from the scope of the invention as defined in the following
claims.
* * * * *